Generally, printing of UV curable inks on paper is limited by the speed at which a UV-based polymerization reaction in the ink occurs. That reaction establishes solidification of the ink and promotes bonding between the ink and the paper surface. As coated papers are also known, the bonding of the ink may be with regard to an outer surface of a coated paper. The extent of bonding between the ink and the paper surface or other layer is typically improved by allowing for longer reaction and/or curing times. However, longer time periods reduce process throughput and thus increase costs.
In addition to, or instead of curing of UV curable inks, other radical polymerizing processes can occur along a face of paper or coated paper. For example, curing of UV curable adhesives can occur in lamination or over-lamination processes, or in cold foil stamping. Another example involves electron beam (EB) curing of EB curable inks.
Although UV curable coating compositions are known which promote printability, these compositions contain residual monomers, oligomers, and/or photoinitiators. Residual monomers, oligomers, and/or photoinitiators may be detrimental to the environment, hinder recyclability, and/or potentially present health issues if used in association with packaging for food, consumables, or health care products.
Accordingly, a need exists for a strategy to improve the extent of bonding of UV curable compositions with paper while increasing processing speeds and avoiding the noted potential environmental and health issues.